Mycotoxin Analysis: What’s new?

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What are mycotoxins?

Mycotoxins are secondary metabolites that are naturally produced by a wide range of specific fungal species as part of their metabolism.

These fungi occur abundantly in our surroundings and food production systems. In fact, they comprise an entire organism Kingdom, separate from plants, animals and other Eukaryotes and they include yeasts, molds and mushrooms.

Many of these species play a symbiotic role with humans due to the critical roles that fungal metabolism plays in the decomposition of organic matter, as a nutritious human food source and the fermentation of numerous foods and beverages.

However, as previously mentioned, many of these organisms also produce harmful bioactive compounds called mycotoxins. In fact, the word “mycotoxins” is named from the combination of the Greek words “mykes” and “toxon” which loosely translates to “mold” and “poisonous arrow”!

Where do mycotoxins occur?

Common food sources

The occurrence of fungi in our food is unavoidable.

Not only are they abundant in our surroundings, but they are also able to withstand several of the common food processing steps that would normally be harmful to other microorganisms. Some of these processing steps include high temperature and pressure treatments as part of food preservation.

Although not all fungi produce mycotoxins, some of the more common foods that are notoriously high in mycotoxins include:

  • Grains (including corn, wheat, barley and rye)
  • Nuts (including peanuts, pistachios and Brazil nuts)
  • Sugar (sugar cane and sugar beets)
  • A variety of cheeses
  • Dietary supplements
  • Baby formula and food
  • Alcoholic beverages
  • Dried fruits
  • Coffee beans
  • Chocolate

Environmental sources

Aside from everyday exposure to mycotoxins via our food sources, some people endure higher levels of exposure through their living situations and/or work environments through inhalation.

Fungal metabolism has the ability to degrade building materials and infrastructure under ideal growth conditions. Therefore, people that are continuously exposed to contaminated buildings, either at work or at home, will inevitably experience high levels of mycotoxin exposure that could have detrimental effects on their health.

Furthermore, occupational exposure poses another layer of health threats to those affected. Workers in the fields of agriculture and food processing like bakeries and mills are more commonly exposed to harmful mycotoxins. Monitoring of the level of inhalation with these subjects should be ongoing.

Current research is also exploring the impact of global warming and climate change on fungal metabolism. Results are revealing that global warming is providing more unfavourable growing conditions for fungi, thereby causing them to produce more mycotoxins under environmentally stressful conditions.

What are the threats?

Mycotoxins in humans

According to the World Health Organization (WHO), food-borne mycotoxins can affect human health in one of two ways:

  1. Acutely: Showing severe symptoms of poisoning directly following ingestion of mycotoxin-contaminated food.
  2. Long-term: Showing long-term detrimental effects on health that includes the development of cancers and immune deficiency.

Prevention and treatment of these health threats rely on appropriate identification and diagnosis of the specific types of mycotoxins responsible. Although numerous unique strains of fungi are responsible for mycotoxin infection, the most common culprits resurface more frequently and often require action:

Common harmful mycotoxins

Aflatoxins.

Commonly produced by various Aspergillus mold species, aflatoxins are amongst the most poisonous mycotoxins.

Exposure to large amounts of these aflatoxins can be life-threatening through acute poisoning (aflatoxicosis) due to liver damage. They have also been implicated in DNA damage that causes cancer in humans and animal species through genotoxicity.

Crops that are commonly affected include:

  • Cereals (wheat, rice, corn)
  • Oilseeds (soy, peanut, sunflower)
  • Spices (chili peppers, black pepper coriander, turmeric, ginger)
  • Tree nuts (pistachio, almond, walnut, Brazil nut)

Aflatoxins are further spread through the milk of animals that are fed contaminated feed.

Ochratoxin A.

Ochratoxin A is commonly produced by various Aspergillus and Penicillium species and causes kidney damage. It also impacts the immune system and it has been linked to harmful effects on fetal development in animals, although similar impacts on humans are still being investigated.

Ochratoxin A predominantly develops during storage of crops that include cereals, coffee beans, dry vine fruits, wine and grape juice, spice and licorice according to the WHO.

Patulin.

Patulin is commonly produced by a variety of molds that include AspergillusPenicillium and Bassochlamys species.

These mycotoxins are most strongly linked to apples and apple juices made from infected fruit and are known for acute symptoms of nausea, gastrointestinal disturbances and vomiting in humans. Similar to Aflatoxins, these Patulin mycotoxins are considered to be genotoxic.   

Trichothecenes.

Trichothecenes are commonly produced by Fusarium species that exist in the soil and are strongly linked to numerous cereal crops. Furthermore, the type of trichothecene is often specific to certain cereal crops.

According to the WHO, these trichothecenes can be acutely toxic to humans and causes irritation to the skin, and intestinal mucosa and cause diarrhea shortly after exposure to the mycotoxin.

Furthermore, some specific trichothecenes like zearalenone (ZEN) have estrogenic effects, particularly shown to cause infertility in pigs. Others have been implicated in oesophageal cancer in humans.

Current methods of analysis

Mycotoxins are unavoidable and potentially dangerous to food security and human health. They are also highly diverse in composition and due to their low molecular weight, hold unique challenges for the application of appropriate screening methods in a laboratory setting.

Fortunately, mycotoxin analyses are ever-evolving and were recently reviewed in detail by at least two groups of researchers (Kizis et al., 2021, Tittlemier et al., 2022). Their findings of the current appropriate laboratory analyses available for mycotoxin screening are vast and selecting suitable combinations of analyses for the specific mycotoxin target requires expert knowledge regarding these currently available methods.

In the process of sample preparation, mycotoxins are notoriously difficult to extract.

They are often unevenly distributed in raw materials being investigated and the sample matrix has to be effectively homogenized in the laboratory before further sample preparation.

Current advances are focused on simultaneous multi-mycotoxin quantification, facilitated by the development of powerful instrumentation tools over the past decade. Some of these developments include coupling classic with modern analytical techniques. Some of these combined techniques can include:

Chromatographic Analytical Methods

Spectroscopic and Spectrometric Methods

  • Fourier-Transformed Infrared (FTIR) Spectroscopy
  • Surface-Enhanced Raman Spectroscopy (SERS)
  • Direct Analysis in Real Time (DART)
  • Nuclear Magnetic Resonance (NMR) Spectrometry

Immunochemical-Based Methods

  • Enzyme-Linked Immunosorbent Assay (ELISA)
  • Lateral Flow and Flow-through Immunoassays (LFIA, FTIA)
  • Flow Injection Immunoassay (FIIA)
  • Chemiluminescence Immunoassay (CLIA)
  • Fluorescent Polarization Immunoassay (FPIA)
  • Fluorometric Assays
  • Biosensors

Molecular Methods

  • qPCR
  • RNASeq

Take-home message

Mycotoxins can be a threat to food security and human health. As a result, we need expert analytical methods to detect and quantify their presence in our environment, food and even in our bodies.

With the advancement of screening technologies over the past decade, specific techniques can be applied to identify and quantify specific mycotoxins with great specificity from a variety of sources.

However, applying the appropriate techniques is paramount to achieving the desired results.

If you or your business requires mycotoxin analysis, backed by experts in their field, reach out to  LabSPACE Africa to start optimising a protocol for your specific needs. We look forward to hearing from you soon!

References

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